Cinci Toolmaster 1D, quill feed works fine. A couple years back it quit on me, I did a full tear down of the quill feed gear box (it wasn’t a big deal), found a small pin had sheared off. Why the pin sheared I can’t explain, since there was no event.
True, I don’t use the quill feed very often (ie. boring etc as others have said), but then I don’t use the Y axis feed very often, or a facing head very often, heck some machines don’t get used but once a year - I still want everything to work when the time comes.
Take it apart, figure it out, fix it (there is probably a YouTube video on it) - that is part of the fun of this hobby.